The chemical composition of almond hulls has been the source of previous comment in the literature. For example, in U.S. Pat. No. 4,482,761 to Chao there is disclosed the presence of myo-inositol and other sugar alcohols, and of sugars, in almond hulls. The water extract of almond hulls is disclosed. It is sometimes referred to herein as "almond fruit syrup". In this patent, the use of molecular sieves to seperate these useful compounds from the water extract is also disclosed. Sequeira et al, "The carbohydrate Composition of Almond Hulls", J. Agri. Food Chem. Vol. 18 (1970) pp. 950-951 provides another discussion of the compostion of almond hulls.
Almond hulls are a natural product forming a part of the almond fruit itself. They are produced as a by-product of the process of producing the most- utilized part of the almond fruit, namely the stone.
It is not a matter of common knowledge, nor well understood in industry and commerce, that the source of the almond nut is a fruit tree. The sweet almond (Prunus amygdalus, or Amygdalus communis) is specifically a stone fruit (drupe), in which the fleshy part, the mesocarp or "hull", is drived from the ovary of the flower and suurounds the shell (endocarp), teguement (thin papery covering ), and finally the stone or "nut" itself. Almond trees are currently cultivated commercially solely for the value of the edible nut, or in the case of the bitter almond, for the flavoring extracts expressed from the otherwise inedible nut. Almonds are most closely related to other stone fruit, such as peach (Prunus persica), apricot (P. armeniaca) and plum (P. domestica, P. instititia, et al.) in which the stone is indeed a stone in the common understanding and is not edible, whereas the mesocarp (not referred to as a "hull") is, and it forms the basis for the commercial exploitation of this fruit.
The process of growth, maturation, abcission, and senescense of the almond fruit, is such that early in its growth stage the "hull" can be eaten by humans, when it possesses pleasing taste, texture, and nutritional value. By maturation and thereafter, the hull is leathery in texture and astringent to the taste, although its nutritional value has actually increased. Unfortunately this increase in nutritional values is accompanied by the presence of other chemical components which can temporarily sicken a human.
As recently as thirty years ago, the nutritional value of the almond hull was not sufficiently understood, and after harvest of the nuts, in California, the hulls were either used for landfill, burned for removal, or sometimes burned for their fuel value. Starting about thirty years ago, agricultural scientists in California introduced and pioneered the use of almond hulls in animal feed, primarily cattle, in which animals the chemical components troublesome to humans do not upset the animals, and nutritional value is obtained at low cost.
The inventor in this instant patent application has observed that several chemical components of almond hulls, present after fruit maturation, have individual and important commercial values, and has devised commercial processes to separate and purify them, leaving very little to waste. For example, prior to the introduction of the use of hulls for animal feed, almond hulls had negative or zero commercial value. Currently, for feed usage, almond hulls have a value averaging about $50/ton. The process invention described herein can raise the value of the almond hull (as separate components) to approximately $800/ton. However, this increased recovery depends heavily on deriving as much as possible of high-value products, and on wasting as little as possible of any part of the starting material.
In this invention the starting material is almond hulls, and the product which at the present time commands a high price and enjoys an elastic demand, is inositol. It is an object of this invention to increase the yield of inositol from almond hulls. Fortuitously, the trade-off is a reduction in products of much lesser value, sometimes with no such reduction at all. For example, some other valuable products (which are not the subject of this invention) such as recoverable vegetable fiber, are not appreciably decreased, if they are decreased at all.